1. Field of the Invention
The present invention relates to a method and apparatus for melting a glycerine soap base for use in casting cakes of glycerine soap.
2. Description of the Prior Art
The use of glycerine soap has gained significantly in popularity in recent years. Glycerine soap is softer than traditional soap that has been cast into cakes of soap for centuries. Moreover, oils of a variety of blends of different fragrances and colorants may be added to glycerine soap. Also, because glycerine soap is transparent or translucent, it lends itself to the addition of ribbons or pieces of solidified glycerine soap into liquified quantities of a soap base. These ribbons or solid pieces become encapsulated within a surrounding quantity of glycerine soap base, once that substance has cooled and solidified. The resulting cakes of soap are aesthetically pleasing for this reason.
Because glycerine soap is a salt of fat, it has a very substantial insulating effect. Therefore, glycerine soap bases absorb a great deal of heat in the melting process. Historically, cakes of glycerine soap were manufactured in five gallon soap pots. The reason the quantities of the soap kettles were so small was due to the large amount of heat required to melt a given quantity of glycerine soap.
Subsequently, different types of steam-jacketed devices were developed for melting glycerine soap. For example, one type of steam-jacketed glycerine soap kettle is manufactured by Groen, a Dover Industries Co. as the Model EE stainless steel, self-contained, steam-jacketed kettle. In this system, the jacket surrounding the kettle is heated by steam in order to melt the glycerine soap base. Another type of steam-jacketed kettle is manufactured by Legion Industries, Inc. under various model designations LEC/HEC.
Steam-jacketed glycerine soap kettles, while capable of melting volumes of glycerine soap significantly larger than was possible with the early five-gallon kettles, have significant disadvantages. The primary disadvantage is the very considerable power requirement for operation. Another disadvantage is that the volume of water required to generate the steam makes the units both bulky and extremely heavy. As a consequence, the cost of operation of steam-jacketed kettles makes their use prohibitively expensive to many glycerine soap manufacturers.
Steam-jacketed types of soap kettles require the application of four to five watts of power for each square inch of surface area of the kettle that is exposed to the steam heating source. Most glycerine soap bases melt at a temperature of between about 120.degree. F. and about 130.degree. F. The application of four to five watts of power per square inch of kettle surface area that is required for operation of conventional, steam-jacketed kettles leads to temperatures in the glycerine exceeding 150.degree. F. This kind of heat scorches the glycerine, thus resulting in a product that is inconsistent in appearance and aesthetically displeasing to the user.
Conventional steam-jacketed glycerine soap melting systems are also subject to problems from corrosion due to minerals in the water employed to generate the steam required. These minerals form scales that clog the system and corrode the steam jacket. This leads to problems that can only be solved by an inordinate amount of preventative maintenance or the use of distilled water. With either approach, the cost of operating these devices is often prohibitively expensive.